Oral drug compliance monitoring using radio frequency identification tags

ABSTRACT

A device useful for oral drug delivery device consisting of: (a) a capsule, tablet or pill designed to disperse in the gastrointestinal system; (b) an RFID tag positioned in the capsule, tablet or pill, the RFID tag comprising an antenna; (c) an object selected from the group consisting of a magnet, a ferromagnetic object, a ferrite object and an electromagnetic shielding object positioned within, over or adjacent the antenna of the RFID tag to alter the antenna characteristics of the RFID tag so that if the RFID tag is interrogated before the capsule, tablet or pill disperses in the gastrointestinal system, the response of the RFID tag is sufficiently altered or attenuated to determine that the capsule, tablet or pill has not dispersed in the gastrointestinal system and so that if the RFID tag is interrogated after the capsule, tablet or pill has dispersed in the gastrointestinal system, the object separates from the RFID tag so that the response of the RFID tag is sufficiently detectable to determine that the capsule, tablet or pill has dispersed in the gastrointestinal system. Alternatively, a switch can be used to signal ingestion of the device, and change the response of the device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Nos. 60/683,141, filed May 20, 2005, and 60/760,903 filed Jan. 20, 2006.

BACKGROUND OF THE INVENTION

The instant invention relates to oral drug compliance monitoring, and, more particularly, to the use of radio frequency identification tags ingested by the patient with a drug formulation.

Non-compliance of patients to drug regimens prescribed by their physicians results in increased cost of medical care, higher complication rates, as well as drug wastage. Non-compliance refers to the failure to take the prescribed dosage at the prescribed time which results in undermedication or overmedication. In a survey of 57 non-compliance studies, non-compliance ranged from 15% to as high as 95% in all study populations, regardless of medications, patient population characteristics, drug being delivered or study methodology (Greenberg, Clinical Therapeutics, 6(5):592-599, 1984).

In the clinical drug stage, accurately measuring compliance can lead to benefits such as: improved statistical reliability of a clinical study; clinical studies being completed sooner; and a determination of the effect of non-compliance as a function of the degree of non-compliance. In the therapeutic stage, accurately measuring compliance has a number of important benefits such as: warning a patient about the potential for developing a drug resistant infection related to poor compliance; and identifying a side effect of a drug related to overdosing.

Compliance to the instructions given to patients during any clinical trial is usually less than 50% in relatively short-term and less than 40% in longer-term trials using traditional methods (e.g., paper diaries) for making entries to show compliance (Vrijens and Goetghebeur, Statist. Med. 23, 531-544, 2004). A clinical trial on chronic pain patients reported only an 11% compliance with as high as 80% fake entries when paper diaries secretly instrumented to tract diary usage were given to patients (Stone et al., Control Clin. Trials. 24, 182-199, 2003) wherein on 32% of study days the paper diary was not opened, yet the compliance entries for those days exceeded 90%. A high incidence of intentional dumping of medications prior to the clinic visit by removing all or most of the medication at one time also occurs in clinical studies (Coutts et al, Arch. Dis. Child. 67, 332-333, 1992; Rand et al, Am. Rev. Respir. Dis. 146, 1559-1564, 1992; Rudd et al, Clin. Pharmacol. Therap. 46, 169-176, 1989; Simmons et al, Chest. 118, 290-295, 2000). Thus, deception among noncompliant patients occurs frequently in clinical trials, and is not often revealed by the traditional monitoring methods. The result is generation of data difficult to interpret and, worse, useless to reliably predict the effectiveness of clinical trials. Better monitoring of the time of actual drug intake will help alleviate many of these issues. For example, blood levels of a drug can be corrected for the time of actual drug intake for better pharmacokinetic/pharmacodynamic interpretations than relying on the time when patient(s) was instructed to take the medication. However, most of the present tracking devices that are utilized in clinical trials only track the initiation of the process of drug intake, i.e., by tracking the time the drug containers are opened or activated. In order to more accurately monitor the compliance of a clinical trial, a more sophisticated method of monitoring the drug intake is needed.

Confirmation of drug compliance by way of direct observation by trained persons is effective but impractical in most situations. Confirmation of drug compliance by blood or urine analysis is also impractical in most situations. Transdermal detection devices attached to the skin of a patient have been developed which detect ingested drug components through the skin and such devices can transmit a signal to a remote receiver at an external site such as a healthcare facility, see U.S. Pat. No. 6,663,846 and USPAP 2005/0031536. Electronic sensor systems have been developed which detect ingested drug components in the breath of a patient, see USPAP 2004/0081587. Radio frequency identification (RFID) tags have been incorporated into drug pills, each tag capable of identifying the type of medication, its dosage, and its lot number by way of a unique code emitted by the tag when interrogated by a corresponding radio frequency “reader”, see U.S. Pat. No. 6,366,206. The RFID of the '206 patent can incorporate a biosensor that detects, for example, a change in pH to determine whether the pill has dissolved and exposed the RFID tag to the environment of the gastrointestinal system. The technology of the '206 patent requires a highly specialized spherical RFID semiconductor and biosensor. It would be an advance in the art if RFID technology could be used in a less complex manner.

SUMMARY OF THE INVENTION

The instant invention is a solution, at least in part, to the above stated problems. The instant invention provides a number of new and improved alternatives for determining drug compliance using RFID tags.

More specifically, the instant invention is a device useful for oral drug delivery, comprising: (a) a capsule, tablet or pill designed to disperse in the gastrointestinal system; (b) an RFID tag positioned in the capsule, tablet or pill, the RFID tag comprising an antenna; (c) an object selected from the group consisting of a magnet, a ferromagnetic object, a ferrite object and an electromagnetic shielding object positioned within, over or adjacent the antenna of the RFID tag to alter the antenna characteristics of the RFID tag so that if the RFID tag is interrogated before the capsule, tablet or pill disperses in the gastrointestinal system, the response of the RFID tag is sufficiently altered or attenuated to determine that the capsule, tablet or pill has not dispersed in the gastrointestinal system and so that if the RFID tag is interrogated after the capsule, tablet or pill has dispersed in the gastrointestinal system, the object separates from the RFID tag so that the response of the RFID tag is sufficiently detectable to determine that the capsule, tablet or pill has dispersed in the gastrointestinal system.

In another embodiment, the instant invention is a device useful for oral drug delivery, comprising: (a) a tablet, pill or capsule designed to disperse in the gastrointestinal system; (b) an RFID tag positioned in the tablet, pill or capsule, the RFID tag comprising a switch, the switch turning on or off in response to conditions in the gastrointestinal system so that if the RFID tag is interrogated before the tablet, pill or capsule disperses in the gastrointestinal system, the response of the RFID tag signifies that the capsule has not dispersed in the gastrointestinal system and so that if the RFID tag is interrogated after the tablet, pill or capsule disperses in the gastrointestinal system, the response of the RFID tag signifies that the tablet, pill or capsule has dispersed in the gastrointestinal system.

In another embodiment, the instant invention is a device useful for oral drug delivery, comprising: (a) a capsule, tablet or pill designed to disperse in the gastrointestinal system; (b) a first non-anti-collision RFID tag positioned in the capsule; (c) a second non-anti-collision RFID tag positioned in the capsule, so that if the RFID tags are interrogated by an RFID reader before the capsule, tablet or pill disperses in the gastrointestinal system, the response of the RFID tags collide and so that after the dispersible material of the capsule has dispersed in the gastrointestinal system thereby allowing the first and second non-anti-collision tags to separate from each other, then the response of the RFID tags is sufficiently different from each other to determine that the capsule has dispersed in the gastrointestinal system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an enlarged view, part in cross-section and part in full, of an oral drug delivery system comprising a gelatin capsule containing a pair of ferrite rings over an RFID tag;

FIG. 2 is an enlarged view of the oral drug delivery system of FIG. 1 after the capsule has dispersed in the gastrointestinal system;

FIG. 3 is an enlarged view, part in cross-section and part in full, of an oral drug delivery system comprising a tablet or pill containing a cylindrical magnet over an RFID tag;

FIG. 4 is an enlarged view, part in cross-section and part in full, of an oral drug delivery system comprising a drug tablet containing pair of ferrite disks positioned at either end of an RFID tag;

FIG. 5 is an enlarged view part in cross-section, part broken away and part in full, of an oral drug delivery system comprising a capsule containing a magnet positioned in a cavity of an RFID tag adjacent the antenna coil of the RFID tag;

FIG. 6 is an enlarged view, part in cross-section and part in full, of an oral drug delivery system comprising a drug tablet containing an iron rod positioned adjacent an RFID tag;

FIG. 7 is an enlarged view, part in cross-section and part in full, of a gelatin capsule containing an RFID tag having an antenna shielded by a cup of gold foil;

FIG. 8 is an enlarged view, part in cross-section and part in full, of a gelatin capsule containing an RFID tag having an antenna shielded by particles of gold embedded in the gelatin capsule;

FIG. 9 is an enlarged view, part in cross-section and part in full, of a gelatin capsule containing an RFID tag having an antenna shielded by particles of gold embedded in a gum arabic coating on the RFID tag;

FIG. 10 is an enlarged view, part in cross-section and part in full, of a drug tablet containing an RFID tag having an antenna shielded by particles of gold embedded in a gum arabic coating on the RFID tag;

FIG. 11 is an enlarged view of an RFID tag having an external fine iron wire shorting the antenna of the RFID tag;

FIG. 12 is an enlarged view of the RFID tag of FIG. 11 after the RFID tag has been exposed to gastric juices for ten minutes to corrode and sever the fine iron wire;

FIG. 13 is an enlarged side view, part in cross-section and part in full, of a switch which turns on if exposed to gastric juices;

FIG. 14 is an enlarged side view, part in cross-section and part in full, of the switch of FIG. 13 after exposure to gastric juices;

FIG. 15 is an enlarged view, part in cross-section and part in full, of a gelatin capsule containing an active RFID tag powered by a kinetic generator and incorporating a conductivity switch;

FIG. 16 is a schematic drawing showing the conductivity switch of FIG. 15 in greater detail;

FIG. 17 is an enlarged view, part in cross-section and part in full, of a drug tablet containing an active RFID tag powered by a battery activated by the action of the electrolyte of the gastrointestinal system in contact with the anode and cathode of the battery;

FIG. 18 is an enlarged view, part in cross-section and part in full, of a drug tablet containing an active RFID tag and a dissolving link switch;

FIG. 19 is an enlarged view, part in cross-section and part in full, of a drug capsule containing an active RFID tag and a switch based sensor;

FIG. 20 is an enlarged view, part in cross-section and part in full, of a drug tablet containing an active RFID tag and a capacitor based switch;

FIG. 21 is an enlarged view, part in cross-section and part in full, of a drug capsule containing an active RFID tag and a temperature based switch;

FIG. 22 is a schematic view of a typical prior art RFID system including a passive RFID tag and an RFID reader or interrogator;

FIG. 23 shows a cross-sectional view of a gelatin capsule containing a pair of passive non-anti-collision RFID tags being interrogated by an RFID reader;

FIG. 24 shows a cross-sectional view of a tablet containing a pair of passive non-anti-collision RFID tags being interrogated by an RFID reader; and

FIG. 25 shows a spaced apart pair of passive non-anti-collision RFID tags being interrogated by an RFID reader.

DETAILED DESCRIPTION

Referring now to FIG. 1, therein is shown an oral drug delivery system 10 of the instant invention, comprising an upper gelatin capsule portion 11 and a lower gelatin capsule portion 12. A Texas Instruments low frequency RFID tag 14 is positioned within the capsule of the system 10. The tag 14 is encapsulated in glass and includes an RFID chip encoded to identify a drug type, dose, lot number etc. The tag 14 includes an antenna. The remaining volume within the capsule of the system 10 is, of course, available to contain a drug formulation 13. A pair of ferrite rings 15 and 16 are positioned around the RFID tag 14 to alter the antenna characteristics of the RFID tag so that if the RFID tag 14 is interrogated before the capsule 11/12 disperses in the gastrointestinal system, the response of the RFID tag is sufficiently altered or attenuated by the ferrite rings 15/16 to determine that the capsule, tablet or pill has not dispersed in the gastrointestinal system.

The term “alter the antenna characteristics of the RFID tag” means to change the resonate frequency of the antenna and/or to reduce the effective signal strength from the antenna. The specific RFID tag used in the instant invention is not critical. For example, the RFID tag does not have to be a low frequency RFID tag. Of course, the RFID tag should be sufficiently encapsulated or otherwise protected so that it works long enough in the environment of the gastrointestinal system to fulfill its purpose. The RFID tag can be pre-programmed or programmable as is well understood in the art. Any type of RFID tag can be used in the instant invention. The RFID tag is preferably a passive RFID tag powered by the a signal from the RFID reader. However, as described below in greater detail, an active RFID tag (powered, for example, by a battery associated with the RFID tag) can also be used in the instant invention as well as a battery assisted passive RFID tag.

Referring now to FIG. 2, when the oral drug delivery system of FIG. 1 is swallowed the capsule portions disperse in the stomach or intestinal tract thereby allowing the RFID tag 14 to separate from the ferrite rings 15/16 so that the response of the RFID tag 14 is sufficiently detectable to determine that the capsule has dispersed in the gastrointestinal system. It should be understood that capsules useful in the instant invention can be made of materials other than gelatin, such as hydroxypropylmethylcellulose. The capsule of the instant invention can also be made of a material, such as poly (N,N-9-diethylaminoethyl methacrylate), which disperses in an acid environment but not in water.

The specific RFID reader used is not critical in the instant invention. Preferably, the RFID reader system is battery powered and contained in a pouch worn around the waist by a belt. The RFID reader can be programmed to sense and record the type of drug(s) and times of administration thereof for later downloading or preferably for wireless downloading to, for example, healthcare professionals who could even send a reminder signal to the system to remind the patient of his/her noncompliance. Alternatively, an RFID reader system can be incorporated into a watch-like appliance worn on the wrist. Or, an RFID reader system could be clipped to a belt not unlike a cell phone clipped to a belt.

Referring now to FIG. 3, therein is shown an enlarged view, part in cross-section and part in full, of an oral drug delivery system 20 comprising a tablet or pill 21 containing a cylindrical magnet 22 over an RFID tag 23. The magnet 22 alters the antenna characteristics of the RFID tag so that if the RFID tag is interrogated before the tablet or pill 21 disperses in the gastrointestinal system, the response of the RFID tag 23 is sufficiently altered or attenuated to determine that the tablet or pill 21 has not dispersed in the gastrointestinal system and so that if the RFID tag 23 is interrogated after the tablet or pill 21 has dispersed in the gastrointestinal system, the cylindrical magnet 22 separates from the RFID tag 23 so that the response of the RFID tag 23 is sufficiently detectable to determine that the tablet or pill 21 has dispersed in the gastrointestinal system.

Referring now to FIG. 4, therein is shown is an enlarged view, part in cross-section and part in full, of an oral drug delivery system 30 comprising a drug tablet 31 containing a pair of ferrite disks 32/33 positioned at either end of an RFID tag 34. The ferrite disks 32/33 alter the antenna characteristics of the RFID tag 34 so that if the RFID tag 34 is interrogated before the tablet 31 disperses in the gastrointestinal system, the response of the RFID tag 34 is sufficiently altered or attenuated to determine that the tablet 31 has not dispersed in the gastrointestinal system and so that if the RFID tag 34 is interrogated after the tablet 31 has dispersed in the gastrointestinal system, the ferrite disks 32/33 separate from the RFID tag 34 so that the response of the RFID tag 34 is sufficiently detectable to determine that the tablet 31 has dispersed in the gastrointestinal system.

Referring now to FIG. 5, therein is shown an enlarged view part in cross-section, part broken away and part in full, of an oral drug delivery system 40 comprising a capsule 41/42 containing a magnet 43 positioned in a cavity of an RFID tag 44 adjacent the antenna coil 45 of the RFID tag 44. The magnet 43 alters the antenna characteristics of the RFID tag 44 so that if the RFID tag 44 is interrogated before the system 40 disperses in the gastrointestinal system, the response of the RFID tag 44 is sufficiently altered or attenuated to determine that the system 40 has not dispersed in the gastrointestinal system and so that if the RFID tag 44 is interrogated after the system 40 has dispersed in the gastrointestinal system, the magnet 43 separates from the RFID tag 44 so that the response of the RFID tag 44 is sufficiently detectable to determine that the system 40 has dispersed in the gastrointestinal system. Alternatively, the cavity of the RFID tag can, for example and without limitation thereto, be filled with a dispersible ferrite composition that will disperse in the gastrointestinal system when the system 40 is ingested.

Referring now to FIG. 6, therein is shown an enlarged view, part in cross-section and part in full, of an oral drug delivery system 50 comprising a drug tablet 51 containing an iron rod 52 positioned adjacent an RFID tag 53. The iron rod 52 alters the antenna characteristics of the RFID tag 53 so that if the RFID tag 53 is interrogated before the system 50 disperses in the gastrointestinal system, the response of the RFID tag 53 is sufficiently altered or attenuated to determine that the system 50 has not dispersed in the gastrointestinal system and so that if the RFID tag 53 is interrogated after the system 50 has dispersed in the gastrointestinal system, the iron rod 52 separates from the RFID tag 53 so that the response of the RFID tag 53 is sufficiently detectable to determine that the system 50 has dispersed in the gastrointestinal system.

Referring now to FIG. 7, therein is shown an oral drug delivery system 10 a of the instant invention, comprising an upper gelatin capsule portion 11 a and a lower gelatin capsule portion 13 a. A Texas Instruments low frequency RFID tag 14 a is positioned within the capsule of the system 10 a. The tag 14 a is encapsulated in glass 15 a and includes an RFID chip 16 a encoded to identify a drug type, dose, lot number etc. The tag 14 a includes a copper coil antenna 18 a having a ferrite core 19 a in communication with the chip 16 a and a capacitor 17 a. The remaining volume 20 a within the capsule of the system 10 a is, of course, available to contain a drug formulation.

The RFID tag can be pre-programmed or programmable as is well understood in the art. The copper coil antenna 18 a and ferrite core 19 a are a preferred antenna system for the RFID tag 14 a of the instant invention because this antenna system is compact even though the wavelength of operation is relatively long. A conventional dipole antenna of the same size as the copper coil antenna 18 a requires a relatively short wavelength of operation which can complicate or even frustrate electromagnetic wave communication through human tissue since such short wavelength radiation is easily absorbed or attenuated by water.

A cup of gold foil 12 a is positioned inside the upper gelatin capsule portion 11 a. When the system 10 a is interrogated with an RFID reader (such as the RFID reader available from, for example, Texas Instruments or from the Stoelting Company (Wood Dale, Ill.) it fails to respond because the gold foil 12 a shields the antenna 18 a. However, when the system 10 a is swallowed the capsule portions 11 a and 13 a disperse in the stomach or intestinal tract thereby freeing the RFID tag 14 a from the shielding effect of the gold foil cup 12 a so that the RFID tag 14 a will now respond to an RFID reader.

The upper gelatin capsule portion 11 a is dispersible in the stomach or intestinal tract. However, it is not critical in the embodiment shown in FIG. 7 that the upper capsule portion is so dispersible since the RFID tag will separate from the gold foil 12 a as long as the lower capsule portion 13 a disperses in the stomach or intestinal tract. Although it is preferable to place the gold foil 12 a inside the upper capsule portion 11 a as shown in FIG. 1, the gold foil 12 a can be placed on the outside of the upper capsule portion 11 a. Although gold is the preferred material to shield the antenna 18 a of the RFID tag 14 a, any metal or other material can be used that is effective to shield the electromagnetic waves and which is approved for ingestion (e.g., iron and nickel are listed by the FDA as Generally Recognized As Safe for ingestion).

It should be understood that capsules useful in the instant invention can be made of materials other than gelatin, such as hydroxypropylmethylcellulose. The capsule of the instant invention can also be made of a material, such as a polymer comprising N,N-9-diethylaminoethyl methacrylate, which disperses in an acid environment but not in water. Similarly, materials such as polymers comprising N,N-9-diethylaminoethyl methacrylate, hydroxypropylmethylcellulose or gelatin can be used instead of gum arabic as a coating material to contain the electromagnetic shielding material.

Referring now to FIG. 8, therein is shown another oral drug delivery system 21 a of the instant invention, comprising an upper gelatin capsule portion 23 a and a lower gelatin capsule portion 22 a. A Texas Instruments low frequency RFID tag 25 a is positioned within the capsule of the system 21 a. The tag 25 a is encapsulated in glass 26 a and includes an RFID chip 27 a encoded to identify a drug type, dose, lot number etc. The tag 25 a includes a copper coil antenna 29 a having a ferrite core 30 a in communication with the chip 27 a and a capacitor 28 a. The remaining volume 31 a within the capsule of the system 21 a is, of course, available to contain a drug formulation. The upper capsule 23 a comprises particles of gold 24 a. When the system 21 a is interrogated with an RFID reader it fails to respond because the gold particles 24 a shield the antenna 29 a. However, when the system 21 a is swallowed the capsule portions 23 a and 22 a disperse in the stomach or intestinal tract thereby freeing the RFID tag 25 a from the shielding effect of the gold particles 24 a so that the RFID tag 25 a will now respond to an RFID reader. The lower gelatin capsule portion 22 a is dispersible in the stomach or intestinal tract. However, it is not critical in the embodiment shown in FIG. 8 that the lower capsule portion is so dispersible since the RFID tag will separate from the lower capsule portion 22 a as long as the upper capsule portion 23 a disperses in the stomach or intestinal tract.

Referring now to FIG. 9, therein is shown another oral drug delivery system 32 a of the instant invention, comprising an upper gelatin capsule portion 34 a and a lower gelatin capsule portion 33 a. A Texas Instruments low frequency RFID tag 35 a is positioned within the capsule of the system 32 a. The tag 35 a is encapsulated in glass 36 a and includes an RFID chip 37 a encoded to identify a drug type, dose, lot number etc. The tag 35 a includes a copper coil antenna 39 a having a ferrite core 40 a in communication with the chip 37 a and a capacitor 38 a. The remaining volume 43 a within the capsule of the system 32 a is, of course, available to contain a drug formulation. The upper end of the RFID tag 35 a is coated with a layer of gum arabic 41 a containing particles of gold 42 a. When the system 32 a is interrogated with an RFID reader it fails to respond because the gold particles 42 a shield the antenna 39 a. However, when the system 32 a is swallowed the gum arabic 41 a disperses in the stomach or intestinal tract thereby freeing the RFID tag 35 a from the shielding effect of the gold particles 42 a so that the RFID tag 35 a will now respond to an RFID reader.

Referring now to FIG. 10, therein is shown another oral drug delivery system 44 a of the instant invention, comprising a tablet or pill 45 a containing a drug formulation. A Texas Instruments low frequency RFID tag 46 a is positioned within the tablet or pill 45 a. The tag 46 a is encapsulated in glass 47 a and includes an RFID chip 48 a encoded to identify a drug type, dose, lot number etc. The tag 46 a includes a copper coil antenna 50 a having a ferrite core 51 a in communication with the chip 48 a and a capacitor 49 a. The RFID tag 46 a is coated with a layer of gum arabic 52 a containing particles of gold 53 a. When the system 44 a is interrogated with an RFID reader it fails to respond because the gold particles 53 a shield the antenna 50 a. However, when the system 44 a is swallowed the tablet or pill 45 a as well as the gum arabic 52 a disperses in the stomach or intestinal tract thereby freeing the RFID tag 46 a from the shielding effect of the gold particles 53 a so that the RFID tag 46 a will now respond to an RFID reader. It should be understood that the layer of gum arabic 52 a containing the gold particles 53 a can also positioned on the surface of the tablet or pill 45 a.

In another embodiment, the instant invention is an oral drug delivery device, comprising: (a) a drug tablet, pill or capsule designed to disperse in the gastrointestinal system; (b) an RFID tag positioned in the tablet, pill or capsule, the RFID tag comprising a switch, the switch turning on or off in response to conditions in the gastrointestinal system so that if the RFID tag is interrogated before the tablet, pill or capsule disperses in the gastrointestinal system, the response of the RFID tag signifies that the capsule has not dispersed in the gastrointestinal system and so that if the RFID tag is interrogated after the tablet, pill or capsule disperses in the gastrointestinal system, the response of the RFID tag signifies that the tablet, pill or capsule has dispersed in the gastrointestinal system. If the RFID tag is an active RFID tag, then the switch preferably turns on the RFID tag after the tablet, pill or capsule has dispersed in the gastrointestinal system (and thus the term “interrogate” throughout the instant invention includes reading the signal from such an active RFID tag). Alternatively, and without limitation thereto, the switch can be used to change a logic function of the RFID tag.

Referring now to FIG. 11, therein is shown an RFID tag 54 a having a thin iron wire 55 a projecting therefrom. The iron wire 55 a serves as a “switch” for the RFID tag, turning the RFID tag off or preferably on when the iron wire 55 a is severed. For example, the iron wire 55 a can be positioned to short the antenna of the RFID tag 54 a so that when the iron wire 55 a is severed, the RFID tag 54 a will respond to an RFID reader. Referring now to FIG. 12, therein is shown the RFID tag 54 a of FIG. 11 after the RFID tag 54 a has been exposed to the acidic conditions of the stomach. The thin iron wire 55 a has been severed by corrosion. The RFID tag of FIG. 11 can thus be placed in a drug capsule or processed in a drug tablet or pill so that when the capsule, tablet or pill is ingested, the RFID tag will then respond to an RFID reader. It should be understood that other materials can be used in place of the iron wire 55 a such as an electrically conductive material that disperses upon exposure in the gastrointestinal system such as a layer of a polymer comprising N,N-9-diethylaminoethyl methacrylate containing a relatively high concentration of gold particles printed on the capsule or tablet so that before its dispersion in the gastrointestinal system, the layer is electrically conductive.

Referring now to FIG. 13, therein is shown a switch system for an RFID tag (not shown) for turning the RFID tag on when the contacts of the switch are closed. The switch system of FIG. 13 includes a small case 56 a having a water permeable disk 57 a and a water swellable gel 62 a. An upper contact 59 a is connected to a first electrical lead 58 a extending from the case 56 a. A lower contact 60 a is connected to a second electrical lead 61 a extending from the bottom of the case 56 a. Referring now to FIG. 14, when the switch system is exposed to water (for example after ingestion into the stomach) the water swellable gel 62 a swells and pushes upper contact 59 a into electrical contact with lower contact 60 a, thereby closing the switch to turn off or, preferably, turn on (or off) the RFID tag. Such an RFID tag can be placed in a drug capsule or processed in a drug tablet or pill so that when the capsule, tablet or pill is ingested, the RFID tag will then respond (or stop responding) to an RFID reader.

Referring now to FIG. 15, therein is shown an enlarged view, part in cross-section and part in full, of one oral drug delivery system embodiment 10 b of the instant invention including an upper gelatin capsule portion 11 b and a lower gelatin capsule portion 12 b. The gelatin capsule 11 b/12 b contains a drug formulation 13 b and an active encapsulated RFID tag 14 b powered by a kinetic generator and incorporating a conductivity detector. The kinetic generator is comprised of a magnet 18 b suspended in a coil 17 b. The capacitor 19 b provides power to RFID circuitry 16 b. When the oral drug delivery system 10 b enters the gastrointestinal system, the gelatin capsule 11 b/12 b, drug formulation 13 b and active RFID tag 14 b are dispersed into the electrolyte solution of the gastrointestinal system and movement of the magnet 18 b in the coil 17 b charges capacitor 19 b to power the RFID circuitry 16 b. Electrodes 20 ab and 20 bc of a conductivity detector system activate the RFID circuitry 16 b when the conductivity detector system senses the conductivity of the electrolyte solution of the gastrointestinal system. RFID circuitry 16 b is connected to antenna 15 b (shown as a copper coil would on a ferrite core) which transmits a signal preferably coded to identify the drug formulation, dose and lot number. Alternatively (and preferably) the kinetic generator system is replaced by a battery.

Referring now to FIG. 16, therein is shown a schematic drawing of the conductivity detector of FIG. 15 in greater detail. A p-FET transistor 22 b and bias resistor 21 b are incorporated to activate the RFID circuitry 16 b from capacitor 19 b when the conductivity of the electrolyte solution of the gastrointestinal system is detected by way of the electrodes 20 ab and 20 bg. Additionally, the p-FET circuit could be replaced by an n-FET, CMOS gate, or other electronic circuits using electronic design methods well known in the art.

Referring now to FIG. 17, therein is shown is an enlarged view, part in cross-section and part in full, of a drug tablet 30 b containing a drug formulation 31 b and an active RFID tag 32 b powered by a battery activated by the action of the electrolyte solution of the gastrointestinal system in contact with the copper anode 33 b and zinc cathode 34 b of the battery. In this embodiment the switch and the RFID power source are unified, i.e., when the RFID tag of tablet 30 b is dispersed in the gastrointestinal system, the electrolyte solution thereof generates the electrical power for the RFID tag 32 b by way of the copper anode 33 b and zinc cathode 34 b. The use of copper in the anode and zinc in the cathode of this embodiment are not critical in the instant invention, i.e., any suitable pair of materials can be used such as carbon and zinc or silver and zinc.

Referring now to FIG. 18, therein is shown an enlarged view, part in cross-section and part in full, of a drug tablet 40 b containing drug formulation 41 b and an active RFID tag 42 b containing RFID circuitry 43 b connected to antenna system 45 b. The RFID circuitry 43 b is powered by battery 44 b. An electrically conducting layer of powdered silver, carbon, or other conductive material in gelatin 48 b provides electrical conduction between electrodes 46 b and 47 b such that when the tablet 40 b disperses in the gastrointestinal tract, the electrolyte solution thereof dissolves the gelatin 48 b and alters the electrical conductivity between electrodes 46 b and 47 b thereby activating RFID circuitry 43 b.

Referring now to FIG. 19, therein is shown an enlarged view, part in cross-section and part in full, of one oral drug delivery system embodiment 50 b of the instant invention including an upper gelatin capsule portion 51 b and a lower gelatin capsule portion 52 b. The gelatin capsule 51 b/52 b contains a drug formulation 53 b and an active encapsulated RFID tag 54 b containing RFID circuitry 55 b connected to antenna system 57 b. The RFID circuitry 55 b is powered by battery 56 b. A pad of water swellable polymer 60 b is positioned so that when the oral drug delivery system 50 b is dispersed in the gastrointestinal system, the electrolyte solution thereof swells the water swellable polymer 60 b causing electrical conductor 58 b to contact electrical conductor 59 b altering the electrical conductivity between the conductors 58 b and 59 b thereby activating RFID circuitry 55 b. It should be understood that the swelling of the water swellable polymer 60 b could easily be arranged to open a switch rather than closing a switch. For example, the swelling of a water swellable polymer could easily be arranged to open a switch of the type shown in FIG. 19 or to break a thin wire. Alternatively, the space between conductors 58 b and 59 b could be filled with a soluble material that would dissolve in the gastrointestinal system allowing the conductors to touch and close the switch. Alternatively, a pressure switch could be used to sense the increased pressure when the active RFID tag of the instant invention was dispersed in the gastrointestinal tract.

Referring now to FIG. 20 therein is shown an enlarged view, part in cross-section and part in full, of one oral drug delivery tablet 61 b of the instant invention. The tablet 61 b contains a drug formulation 62 b and an active encapsulated RFID tag 63 b containing RFID circuitry 64 b connected to antenna system 66 b. The RFID circuitry 64 b is powered by battery 65 b. A film of water swellable polymer 68 b is positioned between first capacitor plate 69 b and second capacitor plate 70 b so that when the oral drug delivery system 61 b is dispersed in the gastrointestinal tract, the electrolyte solution thereof swells the water swellable polymer 70 b altering the capacitance between plates 69 b and 70 b thereby activating RFID circuitry 55 b via electrical conductors 67 b and 68 b. Alternatively the capacitor plates 69 b and 70 b could comprise conductive wires or pads placed near the surface of 63 b such that the dielectric constant of the surroundings would change with ingestion (from air to gastrointestinal electrolyte) altering the capacitance thereby activating the RFID circuitry.

Referring now to FIG. 21, therein is shown an enlarged view, part in cross-section and part in full, of one oral drug delivery system embodiment 70 b of the instant invention including an upper gelatin capsule portion 71 b and a lower gelatin capsule portion 72 b. The gelatin capsule 71 b/72 b contains a drug formulation 73 b and an active encapsulated RFID tag 74 b containing RFID circuitry 75 b connected to antenna system 77 b. The RFID circuitry 75 b is powered by battery 76 b. A thermistor 78 b is in electrical communication with RFID circuitry 75 b so that when the oral drug delivery system 70 b is dispersed in the gastrointestinal tract the RFID circuitry 75 b can sense the change in temperature thereby and begin sending (or altering) its signal via the antenna system 77 b. The RFID circuitry 75 b is preferably programmed to differentiate between the temperature profile with time that occurs when a patient swallows the oral drug delivery system 70 b versus placing the oral drug delivery system 70 b in, for example, a glass of hot water. Alternatively, a temperature sensitive switch can be used instead of the thermistor 78 b.

In another embodiment, the instant invention is an oral drug delivery device, comprising: (a) a capsule, tablet or pill designed to disperse in the gastrointestinal system; (b) a first non-anti-collision RFID tag positioned in the capsule; (c) a second non-anti-collision RFID tag positioned in the capsule, so that if the RFID tags are interrogated by an RFID reader before the capsule, tablet or pill disperses in the gastrointestinal system, the response of the RFID tags collide and so that after the dispersible material of the capsule has dispersed in the gastrointestinal system thereby allowing the first and second non-anti-collision tags to separate from each other, then the response of the RFID tags is sufficiently different from each other to determine that the capsule has dispersed in the gastrointestinal system.

Referring now to FIG. 22, therein is shown a schematic view of a typical RFID system 10 c including a passive RFID tag 11 c and an RFID reader or interrogator 12 c which is usually associated with a host computer or microprocessor system 13 c for data storage and manipulation. The RFID reader or interrogator 12 c transmits a radio frequency energizing/command signal 14 c which is received by the RFID tag 11 c to produce a return data signal 15 c to be received by the reader 12 c.

Referring now to FIG. 23, therein is shown shows a cross-sectional view of a gelatin capsule 21 c/22 c containing a drug formulation 25 c, a first non-anti-collision passive RFID tag 23 c, a second non-anti-collision passive RFID tag 24 c, so that if the RFID tags 23 c and 24 c are interrogated by energizing/command signal 28 c from an RFID reader 26 c before the capsule 21 c/22 c disperses in the gastrointestinal system, the response data signals 29 c of the RFID tags 23 c/24 c “collide”. An active RFID tag is an RFID tag having its own power source, usually a battery. A passive RFID tag is an RFID tag powered by an incoming radio frequency signal. The term “collision” is well understood in the art (see, for example, page 7 of Microchip Technology Inc., microID 13.56 MHz RFID System Design Guide (2004)) as simultaneous data signals from two or more active or passive RFID tags which interfere with each other (“collide”) at the RFID reader. Thus, the term “non-anti-collision RFID tag” means an RFID tag whose data signal will collide with and interfere with the data signal from another non-anti-collision RFID tag at the RFID reader. Since the RFID tags 23 c and 24 c are non-anti-collision tags and since the RFID tags 23 c and 24 c are together in the capsule system 21 c/22 c, the data signals 29 c from the RFID tags 23 c and 24 c collide at the reader 26 c. A computer or microprocessor system 27 c is provided for data storage and manipulation.

Referring now to FIG. 24, therein is shown shows a cross-sectional view of a tablet 30 c containing a drug formulation 31 c, a first non-anti-collision active RFID tag 32 c, a second non-anti-collision active RFID tag 33 c, so that if the RFID tags 32 c and 33 c are interrogated by RFID reader 34 c before the tablet 30 c disperses in the gastrointestinal system, the data signal 37 c of the RFID tags 32 c/33 c “collide” at the reader 34 c. A computer or microprocessor system 35 c is provided for data storage and manipulation.

Referring now to FIG. 25, therein is shown a spaced apart pair of passive non-anti-collision RFID tags 41 c and 42 c (for example if they are separated in the gastrointestinal system) being interrogated by energizing/command signal 45 c/47 c from an RFID reader 43 c. The RFID tags 41 c and 42 c produce data signals 46 c and 48 c to be received by the reader 43 c. The RFID tag 41 c is sufficiently closer to the reader 43 c than the RFID tag 42 c, such that the data signals 46 c and 48 c can be differentiated by the reader 43 c. A computer or microprocessor system 44 c is provided for data storage and manipulation.

Preferably, a pair of active or passive non-anti-collision RFID tags are used in the instant invention. However, it should be understood that more than two such RFID tags can be used. Each non-anti-collision RFID tag is preferably encoded to identify (via its data signal) the drug type, dose and lot number. The specific non-anti-collision RFID tags used in the instant invention are not critical. However, it is preferred that the RFID tag be encapsulated with an inert material such as glass.

EXAMPLE 1

A series of six uniquely coded glass encapsulated animal permanent identification RFID tags (Stoelting Company, Wooddale Ill.) are covered with ferrite rings (National Magnetics Group, Bethlehem Pa.) and placed in gelatin capsules with a simulated drug formulation consisting of food grade lactose (substantially as shown in FIG. 1). The capsules are each interrogated with a portable RFID reader (Allflex ISO Compatible RF/ID Portable Reader Model No. 930002-001) but the reader indicates “No Tag Found”. The capsules are placed in a series of one liter beakers containing 900 mL of USP Simulated Gastric Fluid at 37 degrees Celsius with agitation. The capsules disperse and the reader held at a distance of about 10 centimeters from each RFID tag responds “Tag Found” at the following times: 1.50, 1.80, 1.85, 1.87, 1.88 and 1.95 minutes.

EXAMPLE 2

A series of six uniquely coded glass encapsulated animal permanent identification RFID tags (Stoelting Company, Wooddale Ill.) are covered with ferrite rings (National Magnetics Group, Bethlehem Pa.) and placed in gelatin capsules with a simulated drug formulation consisting of food grade lactose (substantially as shown in FIG. 1 except that three ferrite rings are used). The capsules are each interrogated with a portable RFID reader (Allflex ISO Compatible RF/ID Portable Reader Model No. 930002-001) but the reader indicates “No Tag Found”. The capsules are placed in a series of one liter beakers containing 900 mL of USP Simulated Gastric Fluid at 37 degrees Celsius with agitation. The capsules disperse and the reader held at a distance of about 10 centimeters from each RFID tag responds “Tag Found” at the following times: 1.58, 2.22, 2.33, 3.25, 3.50 and 7.92 minutes.

EXAMPLE 3

A series of uniquely coded glass encapsulated animal permanent identification RFID tags (Stoelting Company, Wooddale Ill.) are covered with a pair of ferrite rings (National Magnetics Group, Bethlehem Pa.) and placed in gelatin capsules with a simulated drug formulation consisting of food grade lactose (substantially as shown in FIG. 1). Four healthy adult beagle dogs are dosed orally with a single capsule containing the RFID tags and ferrite rings. To read radio signals from the RFID tags, the receiver (Stoelting Company, Wooddale Ill.) is held manually within ˜2 cm from the skin of the dog's abdominal region. The time for the first reading of the RFID tag after dissolution of the capsule and release of ferrite sleeves is determined at 1-minute intervals until the first reading is successfully achieved. Subsequent signals are read over time (1,2,4, 8 and 24 hours) thereafter until the RFID tags and ferrite rings passed through the gastrointestinal (GI) tract to be recovered from the collected feces. The time for the RFID tags and ferrite rings to pass through the GI tract and its appearance in the feces is also monitored at each collection interval (e.g., 0-24 and 24-48 hours). The dogs in an initial experiment have free access to feed, both prior to and after dosing. The dogs in a subsequent experiment fasted overnight (−16 hours) then had free access to feed 4 hours after dosing.

In the non-fasted dogs, radio signals are read within 10.3±5.1 minutes after dosing with individual variation of 4 to 16 minutes. Overnight fasting prior to dosing reduces the time to the first signal detection to 6±1 minutes after dosing with a lower individual variation between 5 and 7 minutes. The radio signals emitted by the RFID tag are easily read by the RFID reader at subsequent time points (1,2,4,8 and 24 hours after dosing) indicating location of the device within different regions of the GI tract. All of the devices are recovered from the feces within 24-30 hours from non-fasted and between 24-48 hours from the fasted dogs. Readability of the radio signals emitted from the RFID tags is within 2-3 cm from the animal body with the exception of one tag whose signals are strong enough to be read from 10-12 cm away from the body.

EXAMPLE 4

Two Stoelting Companion Animal Permanent Identification passive RFID tags (Allflex ISO Compliant FDX-B transponders; 12 mm implantable) together in a parallel fashion as shown in FIG. 23 are positioned in a gelatin capsule. The remainder of the capsule is filled with a drug composition. The capsule is interrogated with a portable RFID reader (Allflex ISO Compatible RF/ID Portable Reader Model No. 930002-001) but the reader indicates “No Tag Found” even at a 0 cm read distance. The capsule is placed in 900 mL of USP Simulated Gastric Fluid in a one liter beaker at 37 degrees Celsius with agitation. The capsule disperses after about two minutes and the reader held at a distance of about 10 centimeters from the one liter beaker responds “Tag Found”. Six identical experiments are performed with the following times (in minutes:seconds) to successful read at a read distance of ca. 10 cm: 1:45, 2:02, 1:45, 2:10, 1:45, and 1:49.

EXAMPLE 5

A 433 MHz passive RFID tag is positioned in a gold foil modified gelatin capsule containing a drug formulation substantially as shown in FIG. 7. The capsule is interrogated with a portable RFID reader (Intermec IP3 Intellitag Portabe Reader) but the reader indicates “No Tag Found”. The capsule is placed in 900 mL of USP Simulated Gastric Fluid in a one liter beaker at 37 degrees Celsius with agitation. The capsule disperses after about two minutes and the reader held at a distance of about 10 centimeters from the one liter beaker responds “Tag Found”.

EXAMPLE 6

A 433 MHz active RFID tag having a conductivity switch is positioned in a large gelatin capsule containing a drug formulation substantially as shown in FIG. 15 (except the RFID tag is battery powered and the antenna is spiral wound in a dielectric). The capsule is placed in a plastic wire screen basket placed in the center of a 50 liter polyethylene tank containing 40 liters of USP Simulated Gastric Fluid at 37 degrees Celsius with agitation. A receiving dipole antenna is positioned at the bottom of the tank. Another receiving dipole antenna is positioned outside the tank. The gelatine capsule disperses in the simulated gastric fluid and the conductivity switch turns on the RFID tag which then transmits its 433 MHz signal. The signal strength received by the antenna in the tank is about 5 nanowatt. The signal strength received by the antenna outside the tank held against the tank is about 0.1 nanowatt. The signal strength received by the antenna outside the tank held 70 centimeters away from the tank is about 0.01 nanowatt. An arm held between the tank and the antenna slightly (2-3 dB) reduces the signal strength received by the antenna.

The minimum detectable signal strength received by the antenna outside the tank held even further from the tank is estimated to be about 0.0001 nanowatt. The signal strength received by the antenna outside the tank is only slightly dependent (a variation of about 1-5 dB) on the position of the antenna of the RFID tag.

CONCLUSION

While the instant invention has been described above according to its preferred embodiments, it can be modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the instant invention using the general principles disclosed herein. Further, the instant application is intended to cover such departures from the present disclosure as come within the known or customary practice in the art to which this invention pertains and which fall within the limits of the following claims. 

1. A device useful for oral drug delivery, comprising: (a) a capsule, tablet or pill which will disperse in the gastrointestinal system; (b) an RFID tag positioned in the capsule, tablet or pill, the RFID tag comprising an antenna; (c) an object selected from the group consisting of a magnet, a ferromagnetic object, a ferrite object and an electromagnetic shielding object, the object positioned within, over or adjacent the antenna of the RFID tag to alter the antenna characteristics of the RFID tag so that if the RFID tag is interrogated before the capsule, tablet or pill disperses in the gastrointestinal system, the response of the RFID tag is sufficiently altered or attenuated to determine that the capsule, tablet or pill has not dispersed in the gastrointestinal system and so that if the RFID tag is interrogated after the capsule, tablet or pill has dispersed in the gastrointestinal system, the object separates from the RFID tag so that the response of the RFID tag is sufficiently detectable to determine that the capsule, tablet or pill has dispersed in the gastrointestinal system.
 2. The device of claim 1, wherein the object of element (c) disintegrates in the gastrointestinal system.
 3. The device of claim 1, wherein the object of element (c) separates from the RFID tag in the gastrointestinal system.
 4. The device of claim 1, wherein the RFID tag is selected from the group consisting of an active RFID tag and a passive RFID tag.
 5. The device of claim 4, further comprising a drug formulation positioned in the tablet, pill or capsule.
 6. A device useful for oral drug delivery, comprising: (a) a tablet, pill or capsule designed to disperse in the gastrointestinal system; (b) an RFID tag positioned in the tablet, pill or capsule, the RFID tag comprising a switch, the switch turning on or off in response to conditions in the gastrointestinal system so that if the RFID tag is interrogated before the tablet, pill or capsule disperses in the gastrointestinal system, the response of the RFID tag signifies that the capsule has not dispersed in the gastrointestinal system and so that if the RFID tag is interrogated after the tablet, pill or capsule disperses in the gastrointestinal system, the response of the RFID tag signifies that the tablet, pill or capsule has dispersed in the gastrointestinal system.
 7. The device of claim 6, wherein the RFID tag is selected from the group consisting of an active RFID tag and a passive RFID tag.
 8. The device of claim 7 further comprising a drug formulation positioned in the tablet, pill or capsule.
 9. A device useful for oral drug delivery, comprising: (a) a capsule, tablet or pill designed to disperse in the gastrointestinal system; (b) a first non-anti-collision RFID tag positioned in the capsule; (c) a second non-anti-collision RFID tag positioned in the capsule, so that if the RFID tags are interrogated by an RFID reader before the capsule, tablet or pill disperses in the gastrointestinal system, the response of the RFID tags collide and so that after the dispersible material of the capsule has dispersed in the gastrointestinal system thereby allowing the first and second non-anti-collision tags to separate from each other, then the response of the RFID tags is sufficiently different from each other to determine that the capsule has dispersed in the gastrointestinal system.
 10. The device of claim 9, wherein the RFID tag is selected from the group consisting of an active RFID tag and a passive RFID tag.
 11. The device of claim 10, further comprising a drug formulation positioned in the tablet, pill or capsule. 